76 REPORT OF THE COMMISSIONER OF AGRICULTURE. 



largely interested in determining correctly the materials composing the 

 fabrics which pass through the custom-house. 



There are a number of drawings illustrating the methods employed 

 by me in detecting the presence of animal and vegetable starch and 

 cellulose in various parts of the animal economy. The investigations 

 to which these drawings relate are still in progress, but the great ma- 

 jority of the drawings relate to the leading families, orders, and genera 

 of cryptogamic plants or fungi, of which by far the greater number are 

 microscopic in size. The latter are often visible to the naked eye when 

 massed together in large numbers, ])resenting,in some cases, the appear- 

 ance of a pigment on the surface of the plants upon which they fasten. 

 In such cases the microscope sometimes reveals millions of spores to the 

 square inch. The ravages of these minute vegetable organisms are in- 

 credible in their extent. The potato has at times been threatened al- 

 most with extinction. Grasses have been affected by them, and the 

 cereals throughout large districts have at times suffered blights so 

 serious and so often repeated, that the farmer has been almost ready to 

 abandon their cultivation in despair. Fields of hops, vineyards, and 

 orchards have withered under their blighting touch, and in lower lati- 

 tudes they have assailed coffee-plantations and groves of orange, lemon, 

 and olive trees with equally fatal results. Even the hardy forest-trees 

 have not in all cases escaped their devastating influence, and at the 

 present moment many of the stately maples in the public grounds of 

 our cities are withering under the insidious attacks of these minute 

 destroyers. In short, there is hardly any department of agriculture, 

 horticulture, or forestry that can claim exemption from their ravages j 

 and the importance of a correct knowledge of their characteristics, 

 modes of propagation, and development, and the conditions under which 

 they tend to flourish or decay, can hardly be overestimated. As a con- 

 tribution toward the dissemination of such knowledge, the collection 

 just described possesses a high practical value. 



No large collection of well-executed drawings of cryptogamic plants 

 has heretofore existed in this country; but by the assistance of Dr. M. 

 C. Cooke, of London, and others, I have been able to supply the defect, 

 and have formed a collection which will be of i)ermaneut value to my- 

 cologicnl science in America. The drawings, nearly all of which were 

 made from nature for the special purpose to which they are now des- 

 tined, exhibit a high degree of delicacy and finish. 



Mushrooms in their composition more nearly resemble flesh than any 

 other vegetable. Dr. Marcet proved that, like animals, they absorb a 

 large quantity of oxygen, and give out in return carbonic acid, hydro- 

 gen, or azotic gas. Chemical analysis demonstrates the presence in 

 their structure of the several components of which animal matter is 

 formecl, many containing sugar, gum, resin, fungic acid, various salts, 

 albumen, adipocero, and ozmazone, which last " is that principle which 

 gives flavor to meat-gravy," according to Dr. Badham. 



Fungi are applicable to other than culinary uses, though their most 

 important use is the gastronomic one. To obviate the difiiculty arising 

 from the prejudice against the wholesomeness of any mushroom, Mr. 

 Berkeley recommends a good quantity of bread to be eaten with them. 

 He is of opinion that mushrooms are only indigestible when eaten alone 

 or in imprudent quantity. Of course this remark applies equally to any 

 sort of mushroom, though it is made with reference to the one in famil- 

 iar use. 



As an indirect but very im'portant article of diet, the tiny fungus 

 known as ^' yeast '^ stands iire-eminent» It is composed of globular cells, 



